how to conquer invasive cloverlike plant?

There is an invasive plant in Houston which spreads primarily through corms, somewhat resembles clover and loves to put their corms right under your favorite plants. If you dig them out [there are millions of them] and split a corm you will have multiplied the next crop. I have hand dug and removed thousands, put down weed barrier, topped with mulch and thereby temporarily slowed the progress of this evil weed, but know in my heart it will return with a vengeance. BTW the flowers are sweet little pinkish purple viola like clusters. Thank you.